The present invention relates to junctions between cables.
More particularly, the present invention relates to protecting and insulating junctions between cables.
It is frequently necessary to insulate and protect junctions between cables, such as electric cables. In effecting junctions between cables, for example telephone or power cables, on site, many problems arise in meeting the necessary requirements. Some of these requirements are continuity of insulation and grounding, rendering the joint waterproof and proof against attack by various chemical agents, and mechanical strength and resistance to tension, compression, flexing and impact.
It has been proposed, for example in U.S. Pat. No. 3,455,336, the disclosure of which is incorporated herein by reference, to use sleeves or tubes of heat-shrinkable material, which may or may not be longitudinally split, as protection and insulation for joints in electric cable. The sleeve in its initial, stressed state is of such a diameter that it may be readily moved into position. On the application of heat, the sleeve shrinks so that it fits tighty over the joint.
Since cables are frequently pressurized and must be waterproof, it may be necessary to coat a portion of the inner wall of the heat-shrinkable sleeve with a sealing compound, for example, a mastic or a hot-melt adhesive. When the sleeve is heated, the sealing compound is melted and forms a water-tight and pressure-tight seal between the sleeve and the cable. Protection sleeves, for functions of the type discussed above, suffer from the disadvantage that, in certain cases, they cannot easily be opened up for repair or modification, for example, the feeding in of extra cables, without necessitating complete renewal of the junction.
In copending application U.S. Ser. No. 395,546, filed Sept. 10, 1973 since abandoned, the disclosure of which is incorporated herein by reference, there is disclosed a junction assembly which can readily be opened up for repair or modification and resealed to form a water and pressure tight joint. The junction consists essentially of a relatively rigid longitudinally split tube provided with support means, preferably rings to be positioned one at each end of the tube, and a heat-shrinkable sleeve which is shrunk down over the tube. In a preferred embodiment, the inner surface of the end regions of the sleeve are coated with a sealing compound such that on shrinking, the ends of the sleeve are sealed onto associated cables. The middle section of the sleeve disposed over a split tube is preferably not sealed to the split tube. When the junction is to be opened up, the central section of the sleeve is cut away to reveal the split tube. The split tube can then be opened to attend to the splice or junction. After the repair or modification has been made, the split tube may be closed and the joint resealed by means such as, a split heat-shrinkable sleeve whose inner wall is coated with a sealing material and which is provided with means for sealing the split to form a water and pressure tight joint. A suitable closure device is described in previously mentioned U.S. Pat. No. 3,455,336.